<p>My dissertation is about good arguments and why they fail to persuade. Besides being a common experience of everyday life, this is an old worry of Plato's that continues to motivate two contemporary lines of research. The first concerns what makes something a good argument, and the second concerns what a mind must be like to be moved by one. Together, these lines guide my project and divide it into two parts. Part I is about good reasons, specifically epistemic reasons. In my first chapter, I defend epistemic instrumentalism, the position that epistemic reasons are good reasons only relative to one's epistemic preferences. I acknowledge that epistemic instrumentalism opens the door to a terrible proliferation of incompatible preferences,...